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C# Console App, pass multiple parameters to custom ILogger

Searching I've not found the answer I'm looking for. I will only put code snippets here to help ask my question, supplying ALL of the code would not be executable without the entire system.
I'm using the built-in logging in C# to log to Windows Event Viewer and/or the Console. I also wanted to write to a file but not third-party logging, so I wrote my own simple logger that logs the same data to files and works.
My appsettings.json as a second for some configuration parameters like a working folder. I also have a folder path for the logger. What I would like to be able to do is use the same holder path from the setting and not have 2.
appsettings.json
{
"AppSettings": {
"WorkingFolderPath": "C:\\mypath\\",
"HeartbeatIntervalMinutes": 0, // This is seconds when in debug mode.
"FileRetryDelayMinutes": 1,
"PingTimeoutMilliseconds": 200
},
"Logging": {
"LogLevel": {
"Default": "Error",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Warning"
},
"Debug": {
"LogLevel": {
"Default": "Debug"
}
},
"Console": {
"IncludeScopes": true,
"LogLevel": {
"Default": "Debug"
}
},
"EventLog": {
"LogLevel": {
"Default": "Warning"
}
},
"FileLog": {
"Options": {
"FolderPath": "C:\\mypath\\",
"RetentionDays": 5
},
"LogLevel": {
"Default": "Debug"
}
}
}
}
As you see in this file I have a "WorkingFolderPath" setting I'd like to use that as my path in my "FileLog" logger and not have to specify a path there as well.
Program.cs
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.UseWindowsService()
.ConfigureLogging((context, logging) =>
{
logging.ClearProviders();
logging.AddConsole();
logging.AddDebug();
logging.AddEventLog(new EventLogSettings()
{
SourceName = "FreshIQAppMessagingService"
});
logging.AddFileLogger(options =>
{
context.Configuration.GetSection("Logging").GetSection("FileLog").GetSection("Options").Bind(options);
});
})
.ConfigureAppConfiguration((hostContext, config) =>
{
config
.SetBasePath(ApplicationPath)
.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
.AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", optional: true, reloadOnChange: true);
config.AddEnvironmentVariables();
})
.ConfigureServices((hostContext, services) =>
{
services.Configure<Configuration>(hostContext.Configuration.GetSection("AppSettings"));
services.AddHostedService<Service1>();
services.AddHostedService<Service2>();
services.AddHostedService<Service3>();
services.AddHostedService<Service4>();
});
Here it's getting the options and passing them in. What I've not been able to figure out is how to change my classes so that I can send in the "WorkingFolderPath" from the top of the appsettings instead of the one with the options with the FileLog logger.
logging.AddFileLogger(options =>
{
context.Configuration.GetSection("Logging").GetSection("FileLog").GetSection("Options").Bind(options);
});
FileLoggerExtensions.cs
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System;
namespace FreshIQAppMessaging.Logging
{
public static class FileLoggerExtensions
{
public static ILoggingBuilder AddFileLogger(this ILoggingBuilder loggingBuilder, Action<FileLoggerOptions> configure)
{
loggingBuilder.Services.AddSingleton<ILoggerProvider, FileLoggerProvider>();
loggingBuilder.Services.Configure(configure);
return loggingBuilder;
}
}
}
FileLoggerProvider.cs
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System.IO;
namespace FreshIQAppMessaging.Logging
{
[ProviderAlias("FileLog")]
public class FileLoggerProvider : ILoggerProvider
{
public readonly FileLoggerOptions Options;
public FileLoggerProvider(IOptions<FileLoggerOptions> options)
{
Options = options.Value;
if (!Directory.Exists(Options.FolderPath))
{
Directory.CreateDirectory(Options.FolderPath);
}
}
public ILogger CreateLogger(string categoryName)
{
return new FileLogger(this);
}
public void Dispose() { }
}
}
FileLogger.cs
using Microsoft.Extensions.Logging;
using System;
using System.Globalization;
using System.IO;
namespace FreshIQAppMessaging.Logging
{
public class FileLogger : ILogger
{
protected readonly FileLoggerProvider _fileLoggerProvider;
public FileLogger(FileLoggerProvider fileLoggerProvider)
{
_fileLoggerProvider = fileLoggerProvider;
}
public IDisposable? BeginScope<TState>(TState state)
{
return null;
}
public bool IsEnabled(LogLevel logLevel)
{
return logLevel != LogLevel.None;
}
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
{
if (!IsEnabled(logLevel))
{
return;
}
// Clean up old log files
var logFiles = Directory.GetFiles(_fileLoggerProvider.Options.FolderPath, "*-MyApp.log");
foreach (var logFilePath in logFiles)
{
var logFileName = new FileInfo(logFilePath).Name;
if (DateTime.TryParseExact(logFileName.Substring(0, 8), "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var logFileDate))
{
if (logFileDate.AddDays(_fileLoggerProvider.Options.RetentionDays) < DateTime.Now)
{
File.Delete(logFilePath);
}
}
}
var fullFilePath = $"{_fileLoggerProvider.Options.FolderPath}\\{DateTime.Now.ToString("yyyyMMdd")}-MyApp.log";
var logRecord = $"{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")} [{logLevel.ToString()}] {formatter(state, exception)} {(exception != null ? exception.StackTrace : "")}";
using (var streamWriter = new StreamWriter(fullFilePath, true))
{
streamWriter.WriteLine(logRecord);
}
}
}
}
FileLoggerOptions.cs
using System;
using System.Collections.Generic;
using System.Text;
namespace FreshIQAppMessaging.Logging
{
public class FileLoggerOptions
{
public virtual string? FolderPath { get; set; }
public virtual int RetentionDays { get; set; } = 5;
}
}

You typically don't want to include custom options for your logger inside the Logging section. Most people do something like this instead:
{
"AppSettings": {
"WorkingFolderPath": "C:\\mypath\\",
...
},
"FileLog": {
"FolderPath": "C:\\mypath\\",
"RetentionDays": 5
},
"Logging": {
...
"FileLog": {
"LogLevel": {
"Default": "Debug"
}
}
}
}
You didn't share your options class but I assume you have a property on it named FolderPath. You could then configure your file logger like this:
logging.Services.Configure<FileLoggerOptions>(builder.Configuration.GetSection("FileLog"));
logging.AddFileLogger(options =>
{
options.FolderPath = builder.Configuration["AppSettings:WorkingFolderPath"];
});
You can now remove the FolderPath property from the FileLog object in the appsettings.json file since that value will be set using this line when adding the file logger:
options.FolderPath = builder.Configuration["AppSettings:WorkingFolderPath"];
The options would then look like this:
{
"AppSettings": {
"WorkingFolderPath": "C:\\mypath\\",
...
},
"FileLog": {
"RetentionDays": 5
},
"Logging": {
...
"FileLog": {
"LogLevel": {
"Default": "Debug"
}
}
}
}
I've written a similar logging provider in the Elmah.Io.Extensions.Logging repository and I copied some of the code from there. I tried mapping it to your original code in the question, but there might be something that doesn't match exactly. I hope that you still see the intent behind what I'm trying. You can look inside this repository for inspiration.

System.ArgumentNullException: 'Value cannot be null. (Parameter 'connectionString')' 2

This line is causing an error in my project:
options.UseSqlServer(Configuration.GetConnectionString("SchoolContext")));
Error:
System.ArgumentNullException: 'Value cannot be null. (Parameter 'connectionString')'
I have read through a bunch of similar problems online and I cannot find a change that works. It seems that the parameter inside UseSqlServer() is returning null. This leads me to believe that I have a configuration mistake.
Here is my code for my Startup and json files:
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using ContosoUniversity.Data;
namespace ContosoUniversity
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddRazorPages();
services.AddDbContext<SchoolContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("SchoolContext")));
services.AddDatabaseDeveloperPageExceptionFilter();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
app.UseMigrationsEndPoint();
}
else
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapRazorPages();
});
}
}
}
{
"ConnectionStrings": {
"DefaultConnection": "Server=(***;Database=***;Trusted_Connection=True;MultipleActiveResultSets=true"
},
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information",
"Microsoft.EntityFrameworkCore.Database.Command": "Information"
}
},
"AllowedHosts": "*"
}
Any assistance is appreciated. Thanks.

You are trying to get a connection string called SchoolContext but you only have one in the config called DefaultConnection. So either fix your code:
services.AddDbContext<SchoolContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
Or fix your config:
{
"ConnectionStrings": {
"SchoolContext": "Server=....."
},
// etc...

System.Text.Json.JsonException error message triggered when app is running

I am having an issues with my asp.net core web api application. I am using docker-compose to use elasticsearch and kibana to read logs. I do not get any errors when I build the program. However, once I hit the run button it gives me System.Text.Json.JsonException error message and it is on the line
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}
But the line it says it is on is a blank line. Could I be looking at the incorrect line? Not sure where the line is missing what it is saying because when I try to click on it, nothing happens.
Program.cs
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Serilog;
using Serilog.Sinks.Elasticsearch;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace ElasticSearchLogs
{
public class Program
{
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.UseSerilog((context, configuration) =>
{
configuration.Enrich.FromLogContext()
.Enrich.WithMachineName()
.WriteTo.Console()
.WriteTo.Elasticsearch(new ElasticsearchSinkOptions(node: new Uri(context.Configuration["ElasticConfiguration:Uri"]))
{
IndexFormat = $"{context.Configuration["ApplicationName"]}-logs-{context.HostingEnvironment.EnvironmentName?.ToLower().Replace(".", "-")}-{DateTime.UtcNow:yyyy-MM}",
AutoRegisterTemplate = true,
NumberOfShards = 2,
NumberOfReplicas = 1
})
.Enrich.WithProperty("Environment", context.HostingEnvironment.EnvironmentName)
.ReadFrom.Configuration(context.Configuration);
})
.ConfigureWebHostDefaults(webBuilder =>
{
webBuilder.UseStartup<Startup>();
});
}
}
WeatherForecastController.cs
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace ElasticSearchLogs.Controllers
{
[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
private static readonly string[] Summaries = new[]
{
"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};
private readonly ILogger<WeatherForecastController> _logger;
public WeatherForecastController(ILogger<WeatherForecastController> logger)
{
_logger = logger;
}
[HttpGet]
public IActionResult Get()
{
try
{
var rng = new Random();
if (rng.Next(0, 5) < 2)
{
throw new Exception("Oops what happened??");
}
return Ok(Enumerable.Range(1, 5).Select(index => new WeatherForecast
{
Date = DateTime.Now.AddDays(index),
TemperatureC = rng.Next(-20, 55),
Summary = Summaries[rng.Next(Summaries.Length)]
})
.ToArray());
}
catch(Exception ex)
{
_logger.LogError(ex, "Something bad happened");
return new StatusCodeResult(500);
}
}
}
}
appsettings.json
{
"ApplicationName": "elastic-search-app",
"Serilog": {
"MinimumLevel": {
"Default": "Information",
"Override": {
"Microsoft": "Information",
"System": "Warning"
}
}
},
"ElasticConfiguration": {
"Uri": "http://localhost:9200"
}
"AllowedHosts": "*"
}

I think that you are missing a comma in the configuration json
{
"ApplicationName": "elastic-search-app",
"Serilog": {
"MinimumLevel": {
"Default": "Information",
"Override": {
"Microsoft": "Information",
"System": "Warning"
}
}
},
"ElasticConfiguration": {
"Uri": "http://localhost:9200"
},
"AllowedHosts": "*"
}

Asp.net API not appearing

i am trying to make an angular application that takes an api made from asp.net core but while making the api , it didn't work and appear as planned and didn't know where was the problem...
I made an asp.net core web app.
This is the student.cs file made in the model folder
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace WebAPI101.Model
{
public class Student
{
public int ID { get; set; }
public string Name { get; set; }
public bool Pass { get; set; }
}
}
This is the studentmanager also in model folder
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace WebAPI101.Model
{
public class StudentManager
{
public List<Student> GetResults()
{
List<Student> oList = new List<Student>();
var r = new Random();
for(int i = 0; i < 10; i++)
{
var x = new Student();
x.ID = i;
x.Name = String.Format("Name{0}", i, ToString());
x.Pass = (r.Next() % 2 == 0);
oList.Add(x);
}
return oList;
}
}
}
This is startup.cs
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace WebAPI101
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddRazorPages();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Error");
// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapRazorPages();
});
}
}
}
This is the code that should return aaaaa
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace WebAPI101.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class StudentController : ControllerBase
{
[Route("mariam")]
public string test()
{
return "aaaaa";
}
}
}
I tried to launch the code and it didn't work as planned o the link:https://localhost:5001/api/Student/mariam
While running the application on the previous link it appeared like that:
browser status after running
This is the lanchsettings.json:
{
"iisSettings": {
"windowsAuthentication": false,
"anonymousAuthentication": true,
"iisExpress": {
"applicationUrl": "http://localhost:40854",
"sslPort": 44361
}
},
"profiles": {
"IIS Express": {
"commandName": "IISExpress",
"launchBrowser": true,
"environmentVariables": {
"ASPNETCORE_ENVIRONMENT": "Development"
}
},
"WebAPI101": {
"commandName": "Project",
"dotnetRunMessages": "true",
"launchBrowser": true,
"launchUrl": "api/Student/mariam",
"applicationUrl": "https://localhost:5001;http://localhost:5000",
"environmentVariables": {
"ASPNETCORE_ENVIRONMENT": "Development"
}
}
}
}

The configuration is missing AddControllers and MapControllerRoute calls. Checkout the example below:
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
namespace WebAPI101
{
public class Startup
{
public IConfiguration Configuration { get; }
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
// This method gets called by the runtime. Use this method to add services to the container.
// For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseRouting();
app.UseDefaultFiles();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
"default",
"api/{controller}/{action=Index}");
});
}
}
}

Add `host`, `basePath` and `schemes` to swagger.json using Swashbuckle Aspnetcore

I am using official doc step by step method to configure Swagger UI and generate Swagger JSON file in my ASP.NET core API application.
Get started with Swashbuckle and ASP.NET Core
If I look at my generated swagger.json file - it is missing three important properties host, basePath and schemes
Please help me understand what piece of code can I add so the swagger.json that gets generated will have following mentioned properties/values.
Here is an ideal swagger.json - give attention to the host, basePath and schemes values which are missing if I follow the documentation code in my application
{
"swagger": "2.0",
"info": {
"version": "v1",
"title": "Demo API Title"
},
"host": "some-url-that-is-hosted-on-azure.azurewebsites.net",
"basePath": "/api",
"schemes": ["https"],
"paths": {
"/Account/Test": {
"post": {
"tags": [
"Admin"
],
"summary": "Account test method - POST",
"operationId": "AccountTest",
"consumes": [],
"produces": [
"text/plain",
"application/json",
"text/json"
],
"parameters": [],
"responses": {
"200": {
"description": "Success",
"schema": {
"type": "boolean"
}
}
}
}
}
},
"definitions": {
"NumberSearchResult": {
"type": "object",
"properties": {
"number": {
"type": "string"
},
"location": {
"type": "string"
}
}
}
},
"securityDefinitions": {
"Bearer": {
"name": "Authorization",
"in": "header",
"type": "apiKey",
"description": "Authorization. Example: \"Authorization: Bearer {token}\""
}
},
"security": [
{
"Bearer": []
}
]
}

There are some changes in latest version of Swashbuckle for .netcore
If you wish to change Request URL in Swashbuckle, maybe you are behind API gateway or have custom domain attached to your webapp. Do this.
Create Document filter
public class BasePathDocumentFilter : IDocumentFilter
{
public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
{
swaggerDoc.Servers = new List<OpenApiServer>() { new OpenApiServer() { Url = "hxxt://yoursite" } };
}
}
In your startup file.In services.AddSwaggerGen() method add document filter like this c.DocumentFilter<BasePathDocumentFilter>();

Swagger / open api 3.0 and higher requires the server object. See:
https://swagger.io/specification/#server-object
To set it in your startup like this
app.UseSwagger(c =>
{
c.PreSerializeFilters.Add((swagger, httpReq) =>
{
swagger.Servers = new List<OpenApiServer> { new OpenApiServer { Url = $"{httpReq.Scheme}://{httpReq.Host.Value}" } };
});
});

You can implement and register your own IDocumentFilter and set the desired values there.
public class MyDocumentFilter : IDocumentFilter
{
public void Apply(SwaggerDocument swaggerDoc, SchemaRegistry schemaRegistry, IApiExplorer apiExplorer)
{
swaggerDoc.Host = "some-url-that-is-hosted-on-azure.azurewebsites.net";
swaggerDoc.BasePath = "/api";
swaggerDoc.Schemes = new List<string> { "https" };
}
}
And then register it via
services.AddSwaggerGen(options =>
{
options.DocumentFilter<MyDocumentFilter>();
});

Edit (09SEP20)
Here's some code snippets that applies to version 4.x.x of the asp.netcore Swashbuckle library
In future I might make another post in case the below is more straightforward with new versions (at time of writing it's at version 5.x.x)
sample appsettings.Development.json
{
"Logging": {
"LogLevel": {
"Default": "Warning",
"Microsoft.Hosting.*": "Information"
}
},
"Swagger": {
"ApiVersion": "localhost",
"ApiName": "v1",
"SwaggerRelativeUrl": "/swagger/v1/swagger.json",
"Title": "SalesforceLocationApi"
}
}
sample c# code
namespace My.Api.Settings
{
public class SwaggerSettings
{
public string? ApiName { get; set; }
public string? ApiVersion { get; set; }
public string? SwaggerRelativeUrl { get; set; }
public string? Title { get; set; }
}
}
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Swashbuckle.AspNetCore.SwaggerGen;
using Swashbuckle.AspNetCore.SwaggerUI;
using System;
using System.Reflection;
namespace My.Api
{
public class Startup
{
private readonly IConfiguration _configuration;
public Startup(IConfiguration configuration)
{
_configuration = configuration;
}
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers(ConfigureControllers);
services
.AddSingleton<IHttpContextAccessor, HttpContextAccessor>()
.AddSwaggerGen(SetupUpSwaggerGen);
}
public void Configure(IApplicationBuilder application, IWebHostEnvironment environment, ILoggerFactory loggerFactory, IMapper mapper)
{
if (environment.IsDevelopment())
{
application.UseDeveloperExceptionPage();
}
else
{
application.UseExceptionHandler();
}
application
.UseHttpsRedirection()
.UseSwagger()
.UseSwaggerUI(SetUpSwaggerUi)
.UseRouting()
.UseAuthorization()
.UseEndpoints(endpoints => endpoints.MapControllers());
}
#region Helpers
private void SetupUpSwaggerGen(SwaggerGenOptions options)
{
var swaggerSettings = _configuration.GetSection("Swagger").Get<SwaggerSettings>();
SwaggerConfig.SetUpSwaggerGen(options, swaggerSettings);
}
private void SetUpSwaggerUi(SwaggerUIOptions options)
{
var swaggerSettings = _configuration.GetSection("Swagger").Get<SwaggerSettings>();
SwaggerConfig.SetUpSwaggerUi(options, swaggerSettings.SwaggerRelativeUrl, swaggerSettings.ApiName);
}
#endregion
}
}
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;
using Swashbuckle.AspNetCore.SwaggerUI;
using System;
using System.IO;
using System.Linq;
using System.Reflection;
namespace My.Api
{
public class SwaggerConfig
{
internal class SwaggerDocumentFilter : IDocumentFilter
{
private readonly string _swaggerDocHost;
public SwaggerDocumentFilter(IHttpContextAccessor httpContextAccessor)
{
var host = httpContextAccessor.HttpContext.Request.Host.Value;
var scheme = httpContextAccessor.HttpContext.Request.Scheme;
_swaggerDocHost = $"{scheme}://{host}";
}
public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
{
swaggerDoc.Servers.Add(new OpenApiServer { Url = _swaggerDocHost });
}
}
internal static void SetUpSwaggerGen(SwaggerGenOptions options, SwaggerSettings swaggerSettings)
{
options.DocumentFilter<SwaggerDocumentFilter>();
options.SwaggerDoc(swaggerSettings.ApiName, new OpenApiInfo { Title = swaggerSettings.Title, Version = swaggerSettings.ApiVersion });
options.CustomSchemaIds(type => $"{type?.Namespace?.Split('.').Last()}.{type?.Name}"); //E.g. Acme.Dtos.Gas.Meter.cs --> Gas.Meter
AddXmlComments(options);
}
internal static void SetUpSwaggerUi(SwaggerUIOptions options, string? swaggerRelativeUrl, string? apiName)
{
options.SwaggerEndpoint(swaggerRelativeUrl, apiName);
}
private static void AddXmlComments(SwaggerGenOptions options)
{
var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
options.IncludeXmlComments(xmlPath);
}
}
}
I'm using Swashbuckle.AspNetCore Nuget version 4.0.1
I needed to dynamically add the host depending on where the app is hosted.
This was my fix
I your startup.cs add IHttpContextAccessor to your services
In your swagger config, add a DocFilter, like so:

So in .net core 3 and Open Api - Nswag.AspNetCore version 13.3.2 nuget.
app.UseOpenApi( configure => {
configure.PostProcess = (doc, httpReq) =>
{
doc.Servers.Clear(); //... remove local host, added via asp .net core
doc.Servers.Add(new OpenApiServer { Url = "[YOUR SERVER URL]" }); //... add server
};
});
pulled from this github answer: https://github.com/RicoSuter/NSwag/issues/2441#issuecomment-583721522